An HREM, TEM and SAD study of three-dimensional growth and strain relaxation in (GemSin) superlattices

The cross-sectional structure of (GemSin) superlattices grown on Si(100) at 603 K is investigated via bright-field (BF) images of the diffraction-contrasted transmission electron microscope (CTEM), selected-area diffraction (SAD) and high-resolution electron microscopy (HREM). The superlattices have 3D island structure from the fifth period upward, while the initial few periods have two-dimensional (2D) growth. The boundaries of the 3D islands are approximately parallel to the (011) plane. Analysis of the experimental results suggests that the 3D island structure in (Ge12Si12)50 are formed by the relaxation of the misfit strain.